In　the　construction　of　water　conveyance　tunnels　with　the　shield　method,　accidents　have　occurred　from　time　to　time,　such　as　collapses　and　explosions,　and　it　is　of　practical　significance　to　explore　the　cause　mechanism　of　the　accident.　However,　previous　research　has　not　considered　the　effects　of　dependence　between　risks　on　the　risk　spread.　In　response,　we　propose　a　method　based　on　the　Natural　Killing　Model　(the　N-K　Model)　and　complex　network　theory　to　analyze　the　cause　of　shield　construction　accidents　in　water　conveyance　tunnels.　By　deeply　exploring　the　transmission　mechanism　and　action　intensity　between　system　risks,　this　method　can　scientifically　clarify　the　accident　cause　mechanism　and　provide　support　for　engineering　construction　safety　management.　The　method　constructs　a　risk　index　system.　Secondly,　we　introduce　the　N-K　model　to　reveal　the　risk　coupling　mechanism.　Then,　based　on　complex　network　theory,　we　construct　the　incident　causation　model　and　revise　the　node’s　centrality　with　the　coupling　value.　Finally,　the　network　topology　parameters　are　calculated　to　quantitatively　describe　the　causal　characteristics　of　accidents,　revealing　the　risk　evolution　process　and　critical　causes.　The　research　results　indicate　that　the　key　causes　of　accidents　are　failure　to　construct　according　to　regulations,　inadequate　emergency　measures,　poor　ability　of　judgment　and　decision-making,　and　insufficient　understanding　of　abnormal　situations.　The　front　end　of　critical　links　is　subject　to　human　or　management　risks　and　should　be　carefully　controlled　during　construction.　©　2024　by　the　authors.